NeighborJ Posted September 19, 2016 Posted September 19, 2016 50 pot perc, 50 coarse flake AL, 5 sgrs. Today I mixed up a test batch of silver wave. I have my doubts of this formula, mostly concerning ignition. I made a small 1# batch and tried to cut it from a loaf but it will not cut properly due to the large flake(20 mesh). I quickly gave up on cutting these and proceeded to pump 1/2" comets. I'm not sure of the recommended star sizes and this is why I wanted cut stars, to try various sizes. I also took half of the batch and added 5% dark AL and 10% meal, in an attempt to ease ignition. These comets are on the drying rack and won't be ready for testing any time soon. I'm wondering what should I prime these with? Monocapa? Fence post? I don't think step priming is an option. If this is a good formula I'd like to add some Ti on the next batch.
Mumbles Posted September 19, 2016 Posted September 19, 2016 Just to clarify, Shimuzu calls for "somewhat coarse flake". What that really means it up for debate. I prefer a mixture of bright flake (-200 or -325 mesh), medium flitters (-30+100 or so) and coarse flitters (+30 mesh). Check out some of the Hardt silver formulas to see some suggested ratios, mixtures of metals, and extra additives. I feel they're a bit more representative of mixtures used in practice. There are a lot of ways to make this general class of star. This type of comp is much easier to wet with thin wheat paste by the way. Don't omit the SGRS, but using thin wheat paste instead of water works wonders. You'll want a good hot prime. Shimizu recommends a thermitic prime. Something with a decent amount of silicon should also do the trick. You'll want some BP or easy lighting comp over the top too.
NeighborJ Posted September 19, 2016 Author Posted September 19, 2016 Ok, thanks mumbles. I got the formula from pyrodata and it states coarse flake. I wanted to add finer flake but I didn't want a super fast flash powder type star. I've had those type stars contribute to the burst, causing other stars in the shell to blow blind. I've never added the wheat paste to sgrs it sounds like it should work more like dextrin. I don't mind sgrs but the only part I don't like is the fact that it sticks to my fingers and won't rub off like other binders. Handling the wet stars can be tricky also, they tend to stick to everything and are more likely to rip chunks off the stars rather than become unstuck. Most stars I can use dry comp to coat them but this has so much al. I like the idea of thermitic prime, I really don't think silicon will light this coarse of AL. I've got some research to do and some more experimenting.
FlaMtnBkr Posted September 19, 2016 Posted September 19, 2016 Not sure where Lloyd has been, but his pinball prime was made to light these types of stars. Not sure if there are any special directions so you want to research it if he doesn't comment.
Carbon796 Posted September 19, 2016 Posted September 19, 2016 If the comp was that sticky, it was too wet. Be aware that SGRS needs a tempering period after being wet. A minimum of an hour. There is no reason you can't step prime these stars. It may even be required since they are made with all coarse flake. When I've made them in the past, I only use about 10-15% as coarse flake. You would need to mix up a more appropriate blend of comp, omitting the coarse flake, to step prime with.
NeighborJ Posted September 19, 2016 Author Posted September 19, 2016 Yeah C, you may be correct about over wetting, this comp has only metal fuel and it takes far less water than most comps to activate. Yes I do let these sit for an hour in a ziplock bag, in my warm drying box. It has been near 100% humidity since I made them, so drying is going very slow. I am thinking of adding my titanium,dragon egg dust to Monocapa prime. It's just the stuff which shook out of the batch and passed all my sizing screens. I know it would be an expensive prime but at this point it's free and it is the most readily available and ignitable thermite type comp I have. If that won't work, nothing will, unless someone knows a type of nuclear-powered fusion prime.
Mumbles Posted September 21, 2016 Posted September 21, 2016 Maybe not nuclear fusion, but these two primes may light the atmosphere on fire. If they don't work, nothing will. Both will need something over the top to help with ignition. I've seen the following formula from two or three different sources so I'm not sure who to attribute it to. I believe it's from Lancaster or English in origin. This formula is in Hardt too, but in percentages. KNO3 - 40Silicon - 40Meal - 20Dextrin - +5% Red Thermit from Shimizu (FAST, p 216)Red Lead - 80Ferro-silicon - 20Binder of choice +5% I'm fairly certain just silicon would work. The Ferro-Si in question is about 90% Si anyway.
pyrojig Posted October 2, 2016 Posted October 2, 2016 One thing that I might add that was kind of a revelation ...... The charcoal in the prime /bp meal + prime comp etc. Needs to be porous in nature , and reactive . Pine and paulownia seem to be the two I use extensively . "Jopettes" was the one that clarified the science behind this reactive char being the best candidate. Hope this helps ...I have reduced my ignition issues to about 0% failures . Step priming is a helpful way to insure ignition. Why do all the work and spend the $ on heavy metal stars and have a crappy ignition ? Take the extra steps and reep the rewards .
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